Skill Scaffolder

Skill Scaffolder

This skill provides comprehensive instructions and templates for creating new skills in the pitlane-agent project. Use this skill when you need to scaffold new capabilities, add scripts, or set up test infrastructure.

When to Use This Skill

Use this skill when:

• Adding new functionality: Creating a new skill to handle specific user requests
• Building script-backed features: Need a click-based Python script with the skill
• Setting up tests: Creating test infrastructure for new scripts
• Creating skill hierarchies: Building parent skills with multiple related subskills

Naming Conventions

Skills

• Directory name: kebab-case (e.g., skill-scaffolder, f1-analyst)
• YAML name field: Must match directory name exactly
• Markdown title: Title Case (e.g., "Skill Scaffolder", "F1 Data Analyst")

Scripts

• File name: snake_case.py (e.g., event_schedule.py, lap_times.py)
• Business logic functions: snake_case (e.g., get_event_schedule, generate_chart)
• CLI function: Always named cli
• Invocation: python -m pitlane_agent.scripts.script_name

Tests

• File name: test_<script_name>.py (e.g., test_event_schedule.py)
• Test classes: Test<ClassName> (e.g., TestBusinessLogic, TestCLI)
• Test methods: test_<what_it_tests> (e.g., test_cli_success, test_validation_error)

Directory Structure

PitLane-AI/
├── packages/
│   └── pitlane-agent/
│       ├── src/
│       │   └── pitlane_agent/
│       │       ├── .claude/
│       │       │   └── skills/
│       │       │       ├── skill-name/           # Flat skill
│       │       │       │   └── SKILL.md
│       │       │       └── parent-skill/         # Hierarchical skill
│       │       │           ├── SKILL.md          # Parent with table
│       │       │           ├── subskill-1.md     # Subskill 1
│       │       │           └── subskill-2.md     # Subskill 2
│       │       └── scripts/
│       │           └── script_name.py
│       └── tests/
│           └── scripts/
│               └── test_script_name.py

Step 1: Create a Flat Skill

A flat skill is a standalone skill contained in a single SKILL.md file.

Instructions

1. Create the skill directory:

   mkdir -p packages/pitlane-agent/src/pitlane_agent/.claude/skills/your-skill-name
   

2. Create SKILL.md using the template below

3. Customize the template:

   • Replace skill-name with your kebab-case skill name
   • Update description to explain when to use the skill
   • Set appropriate allowed-tools (common: Bash(python:*), Read, Write, Skill)
   • Fill in the skill content with instructions for Claude

Flat Skill Template (SKILL.md)

---
name: skill-name
description: Brief description of when to use this skill. Should explain the trigger conditions.
allowed-tools: Bash(python:*), Read, Write
---

# Skill Title

Introduction paragraph explaining what this skill does and its purpose.

## When to Use This Skill

Use this skill when users ask about:
- **Use case 1**: Describe when this applies (e.g., "Race calendars and event dates")
- **Use case 2**: Another trigger scenario
- **Use case 3**: Additional context

## Step 1: Understand the Request

Provide guidance on how to parse and understand the user's request. Include:
- What parameters to extract
- Default values to use
- How to handle ambiguous requests

## Step 2: Execute the Main Task

Instructions for performing the core functionality. This might include:
- Running a script with bash
- Reading/analyzing files
- Using other tools

### Example Commands

If this skill uses scripts, provide examples:

```bash
python -m pitlane_agent.scripts.script_name --param1 value --param2 value

Step 3: Format the Response

Guidance on how Claude should structure the response to the user:

• What format to use (table, list, prose)
• What information to highlight
• How to handle edge cases

Data Reference (Optional)

If applicable, include reference data like:

• Field descriptions
• Valid values
• Lookup tables
• Common abbreviations

Example Questions and Approaches

Provide 3-5 realistic example questions with suggested approaches:

"Example question 1?"

1. Step to handle it
2. What to do next
3. How to respond

"Example question 2?"

1. Different approach for this scenario
2. Handling variations
3. Response format

Notes

Any important caveats, limitations, or additional context.

## Step 2: Create a Hierarchical Skill

Hierarchical skills have a parent SKILL.md that references multiple subskill markdown files.

### Instructions

1. Create the parent skill directory:
   ```bash
   mkdir -p packages/pitlane-agent/src/pitlane_agent/.claude/skills/parent-skill-name

2. Create the parent SKILL.md with a table of subskills
3. Create separate markdown files for each subskill (e.g., subskill-1.md)
4. Keep hierarchy to 1 level (parent → subskills only)

Hierarchical Parent Template (SKILL.md)

---
name: parent-skill
description: Parent skill managing multiple related subskills. Briefly explain the domain.
allowed-tools: Skill
---

# Parent Skill Title

This skill provides access to multiple related subskills for [domain/topic area].

## Available Subskills

| Subskill | Description | Documentation |
|----------|-------------|---------------|
| subskill-1 | Brief description of what it does | [subskill-1.md](./subskill-1.md) |
| subskill-2 | Brief description of what it does | [subskill-2.md](./subskill-2.md) |
| subskill-3 | Brief description of what it does | [subskill-3.md](./subskill-3.md) |

## How to Use

When a user asks about [topic], determine which subskill is most appropriate based on:
- **Criteria 1**: Use subskill-1
- **Criteria 2**: Use subskill-2
- **Criteria 3**: Use subskill-3

Invoke the appropriate subskill using the Skill tool.

## Example Questions

Map common user questions to the right subskill:

- "Question pattern 1" → Use subskill-1
- "Question pattern 2" → Use subskill-2
- "Question pattern 3" → Use subskill-3

## Notes

Any cross-cutting concerns or general guidance for using these subskills together.

Subskill File Template (subskill-1.md)

# Subskill Title

Detailed instructions for this specific subskill. This file has the same structure as a flat SKILL.md but without the YAML front matter (that's only in the parent).

## When to Use

Specific trigger conditions for this subskill.

## Step 1: [First Step]

Detailed instructions...

## Step 2: [Second Step]

More instructions...

## Example Usage

Examples specific to this subskill...

Step 3: Create a Click-Based Script (Optional)

If your skill needs a Python script to perform actions, create it using click.

Instructions

1. Create the script file:

   touch packages/pitlane-agent/src/pitlane_agent/scripts/your_script_name.py
   

2. Use the template below as a starting point

3. Customize:

   • Replace script_name and main_function with your names
   • Add appropriate click options
   • Implement business logic in the main function
   • Ensure JSON output to stdout
   • Handle errors with JSON to stderr and sys.exit(1)

Click Script Template

"""
Brief description of what this script does.

Usage:
    python -m pitlane_agent.scripts.script_name [OPTIONS]
"""

import json
import sys
from pathlib import Path

import click


def main_function(
    param1: str,
    param2: int,
) -> dict:
    """Business logic function.

    Separate the business logic from CLI handling to make it easier to test.

    Args:
        param1: Description of first parameter
        param2: Description of second parameter

    Returns:
        Dictionary with results in a structured format

    Raises:
        ValueError: If validation fails
        RuntimeError: If operation fails
    """
    # Input validation
    if not param1:
        raise ValueError("param1 cannot be empty")

    if param2 < 0:
        raise ValueError("param2 must be non-negative")

    # Business logic implementation
    # ... your code here ...

    # Return structured result
    result = {
        "param1": param1,
        "param2": param2,
        "status": "success",
        "data": {
            # Your actual results
        }
    }

    return result


@click.command()
@click.option(
    "--param1",
    required=True,
    help="Description of param1"
)
@click.option(
    "--param2",
    type=int,
    default=100,
    help="Description of param2 (default: 100)"
)
@click.option(
    "--output",
    type=click.Path(),
    help="Optional output file path"
)
def cli(param1: str, param2: int, output: str | None):
    """Command description that appears in --help."""
    try:
        result = main_function(param1=param1, param2=param2)

        # Pretty-print JSON output
        output_json = json.dumps(result, indent=2)

        if output:
            # Write to file if specified
            Path(output).parent.mkdir(parents=True, exist_ok=True)
            Path(output).write_text(output_json)
            click.echo(json.dumps({"status": "written", "path": output}))
        else:
            # Print to stdout
            click.echo(output_json)

    except Exception as e:
        # Error output to stderr with exit code 1
        click.echo(json.dumps({"error": str(e)}), err=True)
        sys.exit(1)


if __name__ == "__main__":
    cli()

Common Click Patterns

Multiple values for an option:

@click.option(
    "--driver",
    multiple=True,
    help="Driver abbreviation (can specify multiple)"
)
def cli(driver: tuple[str, ...]):
    drivers = list(driver)  # Convert tuple to list

Boolean flags:

@click.option(
    "--include-testing/--no-testing",
    default=True,
    help="Include testing sessions"
)
def cli(include_testing: bool):
    pass

Choice from list:

@click.option(
    "--session",
    type=click.Choice(['FP1', 'FP2', 'FP3', 'Q', 'S', 'R']),
    required=True,
    help="Session type"
)
def cli(session: str):
    pass

File path:

@click.option(
    "--config",
    type=click.Path(exists=True, dir_okay=False),
    help="Path to config file"
)
def cli(config: str):
    pass

Step 4: Create Tests (Optional)

If you created a script, create comprehensive tests using pytest and click.testing.CliRunner.

Instructions

1. Create the test file:

   mkdir -p packages/pitlane-agent/tests/scripts
   touch packages/pitlane-agent/tests/scripts/test_your_script_name.py
   

2. Use the template below

3. Create two test classes:

   • TestBusinessLogic: Unit tests for business functions
   • TestCLI: Integration tests for CLI interface

Test Template

"""Tests for script_name script."""

import json
from unittest.mock import MagicMock, patch

import pytest
from click.testing import CliRunner

from pitlane_agent.scripts.script_name import cli, main_function


class TestMainFunctionBusinessLogic:
    """Unit tests for business logic functions.

    These tests directly call business functions without going through the CLI.
    Mock any external dependencies (APIs, file I/O, etc.).
    """

    def test_main_function_success(self):
        """Test successful execution with valid inputs."""
        result = main_function(param1="test", param2=100)

        assert result["param1"] == "test"
        assert result["param2"] == 100
        assert result["status"] == "success"
        assert "data" in result

    def test_main_function_validation_error_empty_param1(self):
        """Test that empty param1 raises ValueError."""
        with pytest.raises(ValueError, match="param1 cannot be empty"):
            main_function(param1="", param2=100)

    def test_main_function_validation_error_negative_param2(self):
        """Test that negative param2 raises ValueError."""
        with pytest.raises(ValueError, match="param2 must be non-negative"):
            main_function(param1="test", param2=-1)

    @patch("pitlane_agent.scripts.script_name.some_external_dependency")
    def test_main_function_with_mocked_dependency(self, mock_dependency):
        """Test with mocked external dependencies."""
        # Setup mock
        mock_dependency.return_value = {"data": "mocked"}

        result = main_function(param1="test", param2=100)

        # Verify mock was called correctly
        mock_dependency.assert_called_once()
        assert result["status"] == "success"


class TestCLI:
    """Integration tests for CLI interface using CliRunner.

    These tests invoke the CLI as a user would and verify the output.
    """

    def test_cli_help(self):
        """Test that --help displays usage information."""
        runner = CliRunner()
        result = runner.invoke(cli, ["--help"])

        assert result.exit_code == 0
        assert "--param1" in result.output
        assert "--param2" in result.output
        assert "Command description" in result.output

    def test_cli_success(self):
        """Test successful CLI execution."""
        runner = CliRunner()
        result = runner.invoke(cli, [
            "--param1", "test",
            "--param2", "200"
        ])

        assert result.exit_code == 0

        # Parse JSON output
        output = json.loads(result.output)
        assert output["param1"] == "test"
        assert output["param2"] == 200
        assert output["status"] == "success"

    def test_cli_with_defaults(self):
        """Test CLI with default values for optional params."""
        runner = CliRunner()
        result = runner.invoke(cli, [
            "--param1", "test"
            # param2 should use default value of 100
        ])

        assert result.exit_code == 0
        output = json.loads(result.output)
        assert output["param2"] == 100

    def test_cli_missing_required(self):
        """Test that missing required option shows error."""
        runner = CliRunner()
        result = runner.invoke(cli, [])

        assert result.exit_code != 0
        assert "param1" in result.output or "required" in result.output.lower()

    def test_cli_error_handling(self):
        """Test that errors are properly formatted as JSON to stderr."""
        runner = CliRunner()
        result = runner.invoke(cli, [
            "--param1", "",  # This should trigger validation error
            "--param2", "100"
        ])

        assert result.exit_code == 1

        # Error should be JSON formatted
        error_output = json.loads(result.output)
        assert "error" in error_output
        assert "cannot be empty" in error_output["error"]

    def test_cli_with_output_file(self, tmp_path):
        """Test writing output to a file."""
        runner = CliRunner()
        output_file = tmp_path / "output.json"

        result = runner.invoke(cli, [
            "--param1", "test",
            "--param2", "100",
            "--output", str(output_file)
        ])

        assert result.exit_code == 0
        assert output_file.exists()

        # Verify file contents
        saved_data = json.loads(output_file.read_text())
        assert saved_data["param1"] == "test"

    @patch("pitlane_agent.scripts.script_name.main_function")
    def test_cli_calls_business_logic(self, mock_main_function):
        """Test that CLI correctly calls business logic function."""
        mock_main_function.return_value = {"status": "mocked"}

        runner = CliRunner()
        result = runner.invoke(cli, [
            "--param1", "test",
            "--param2", "100"
        ])

        # Verify business function was called with correct args
        mock_main_function.assert_called_once_with(
            param1="test",
            param2=100
        )

Running Tests

# Run all tests for a script
uv run pytest packages/pitlane-agent/tests/scripts/test_script_name.py -v

# Run specific test class
uv run pytest packages/pitlane-agent/tests/scripts/test_script_name.py::TestCLI -v

# Run specific test method
uv run pytest packages/pitlane-agent/tests/scripts/test_script_name.py::TestCLI::test_cli_success -v

# Run with coverage
uv run pytest packages/pitlane-agent/tests/scripts/test_script_name.py --cov=pitlane_agent.scripts.script_name

Step 5: Verify Setup

After creating your skill, script, and tests, verify everything works:

1. Verify Skill Structure

• SKILL.md exists in correct location
• YAML front matter is valid (name, description, allowed-tools)
• Instructions are clear and actionable
• Templates are properly formatted
• For hierarchical skills: parent links to subskills correctly

2. Test Script Execution

# Test help output
python -m pitlane_agent.scripts.your_script_name --help

# Test with sample inputs
python -m pitlane_agent.scripts.your_script_name --param1 test --param2 100

# Verify JSON output format
python -m pitlane_agent.scripts.your_script_name --param1 test | jq .

3. Run Tests

# Run all tests
uv run pytest packages/pitlane-agent/tests/scripts/test_your_script_name.py -v

# Check coverage
uv run pytest packages/pitlane-agent/tests/scripts/test_your_script_name.py \
  --cov=pitlane_agent.scripts.your_script_name \
  --cov-report=term-missing

4. Test Skill Usage

Try using the skill in a Claude conversation to ensure it works as expected.

Examples

Example 1: Simple Flat Skill (No Script)

A skill that provides guidance without needing a script:

---
name: code-review-helper
description: Assist with code review tasks. Use when user asks for code reviews, style checks, or best practices.
allowed-tools: Read, Glob, Grep
---

# Code Review Helper

This skill helps perform thorough code reviews following best practices.

## When to Use This Skill

Use when users ask to:
- Review code changes
- Check coding standards
- Suggest improvements
- Identify bugs or issues

## Step 1: Understand Scope

Determine what needs to be reviewed:
- Specific files: Use Read tool
- Pattern-based: Use Glob to find files
- Search for patterns: Use Grep

## Step 2: Analyze Code

Review for:
- Code style and formatting
- Potential bugs
- Performance issues
- Security vulnerabilities
- Best practices

## Step 3: Provide Feedback

Structure feedback as:
1. Summary of findings
2. Critical issues (must fix)
3. Suggestions (should consider)
4. Positive observations

Example 2: Script-Backed Flat Skill

The f1-schedule skill is a good example:

• SKILL.md provides instructions
• References event_schedule.py script
• Explains how to use script with different parameters
• Shows how to format responses

Example 3: Hierarchical Skill

A data analysis skill with subskills:

SKILL.md (Parent):

---
name: data-analysis
description: Comprehensive data analysis tools. Use when user needs data processing, visualization, or statistical analysis.
allowed-tools: Skill
---

# Data Analysis

This skill provides access to specialized data analysis subskills.

## Available Subskills

| Subskill | Description | Documentation |
|----------|-------------|---------------|
| data-cleaning | Clean and prepare datasets | [data-cleaning.md](./data-cleaning.md) |
| data-viz | Create visualizations | [data-viz.md](./data-viz.md) |
| statistics | Statistical analysis | [statistics.md](./statistics.md) |

## How to Use

- Data preparation tasks → data-cleaning
- Chart/graph requests → data-viz
- Statistical questions → statistics

data-cleaning.md (Subskill):

# Data Cleaning

Instructions for cleaning and preparing datasets.

## When to Use

Use when data needs:
- Missing value handling
- Outlier detection
- Format standardization
- Deduplication

## Steps...

Common Patterns

Allowed Tools

Choose tools based on what the skill needs to do:

• Read-only analysis: Read, Glob, Grep
• Script execution: Bash(python:*), Read, Write
• File creation: Write, Read, Bash(mkdir:*)
• Hierarchical skills: Skill (to invoke subskills)
• Web access: WebFetch, WebSearch (if needed)

Restrictions

You can restrict Bash usage:

• Bash(python:*) - Only Python commands
• Bash(git:*) - Only Git commands
• Bash(npm:*) - Only npm commands

Error Handling in Scripts

Always handle errors gracefully:

try:
    result = main_function(...)
    click.echo(json.dumps(result, indent=2))
except ValueError as e:
    click.echo(json.dumps({"error": f"Validation error: {str(e)}"}), err=True)
    sys.exit(1)
except Exception as e:
    click.echo(json.dumps({"error": f"Unexpected error: {str(e)}"}), err=True)
    sys.exit(1)

Best Practices

1. Keep skills focused: One skill should do one thing well
2. Provide examples: Include 3-5 realistic example questions
3. Document edge cases: Note limitations and special cases
4. Use consistent formatting: Follow the templates provided
5. Test thoroughly: Ensure scripts work before creating the skill
6. Write clear instructions: Claude should be able to follow without guessing
7. Separate concerns: Business logic separate from CLI handling
8. Type hints: Use Python type hints in all functions
9. JSON output: Always output structured JSON from scripts
10. Test coverage: Aim for >90% coverage with meaningful tests

Troubleshooting

Issue: YAML parsing error

Solution: Ensure YAML front matter has exactly 3 dashes before and after, no extra whitespace

Issue: Script not found

Solution: Verify script is in packages/pitlane-agent/src/pitlane_agent/scripts/ and has .py extension

Issue: Tests failing

Solution: Check imports match the actual module structure, ensure mocks are properly configured

Issue: Click options not working

Solution: Verify option names match function parameters, check types and defaults

Issue: Hierarchical skill table not rendering

Solution: Ensure table has proper markdown format with pipes and dashes, check file paths are relative

Notes

• No automation script: This skill provides instructions only. You'll create files using Write tool.
• Convention adherence: Following conventions ensures consistency across the codebase.
• Test-first approach: Consider writing tests before implementing complex business logic.
• Click is required: All new scripts must use click, not argparse.
• Flat is preferred: Only create hierarchical skills when you have 3+ related subskills.

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